This invention relates to liquid waste and more particularly, it relates to improved oxygenation of liquid waste.
For the treatment of municipal wastewater, aerobic organisms work to consume the toxic material or break it down into a form which is safely discharged. The aerobic organism requires a constant supply of oxygen to survive. Oxygen can be supplied by bubbling air into the liquid waste or, in some cases, pure oxygen is supplied. U.S. Pat. No. 5,200,080 discloses the use of air and pure oxygen for the treatment of liquid waste. However, this patent discloses the use of both non-turbulent flow and turbulent flow and the use of pipe reducers to make the transition from non-turbulent flow to turbulent flow for uniform passage of oxygenated water to multiple eductors.
U.S. Pat. No. 4,085,041 discloses an oxidation and flotation apparatus for the treatment of sewage or other aqueous waste material using oxygen-containing gas bubbles.
U.S. Pat. No. 4,043,771 discloses oxygenation of sewage sludge by forcing the liquid downwardly through a perforated wall into a gas space in a vessel containing the liquid.
U.S. Pat. No. 5,186,841 discloses treating impure water by injecting ozone into a pressurized stream of water.
U.S. Pat. No. 4,226,717 discloses a waste water treatment system that provides an elongated grit chamber within the oxidation vessel.
However, blowing forced air into the liquid has the disadvantage or problem that it is expensive to operate large blowers to provide the necessary volume of air. Another problem with forced air is that a bacteria referred to as noccardia evidenced by large quantities of foam generated in the mixed liquor or aeration tank can develop. The noccardia bacteria can spread to the clarifier or can be carried in the wind with its attendant problems. Yet another problem with the use of forced air is that odors from the treatment system become airborne. Further, microorganisms or airborne pathogens in the aerobic system can be carried in the air and distributed in the vicinity of the sewage plant.
It will be seen that there are many problems attendant the use of forced air in an aeration system of a sewage plant. Thus, there is a great need for a simple, cost effective system that supplies oxygen-bearing gas for waste liquid treatment and that provides for efficient dissolution of the gas in waste liquid.